# -*- coding: UTF-8 -*-
"""
@Time:2021/11/30 22:29
@File:mypage.py
@Author:常雷
@Software:PyCharm
"""
class Pagination(object):
	def __init__(self,current_page,all_count,per_page_num=2,pager_count=11):
		"""
		封装分页相关数据
		:param current_page: 当前页
		:param all_count:    数据库中的数据总条数
		:param per_page_num: 每页显示的数据条数
		:param pager_count:  最多显示的页码个数

		用法:
		queryset = model.objects.all()
		page_obj = Pagination(current_page,all_count)
		page_data = queryset[page_obj.start:page_obj.end]
		获取数据用page_data而不再使用原始的queryset
		获取前端分页样式用page_obj.page_html
		"""
		try:
			current_page = int(current_page)
		except Exception as e:
			current_page = 1

		if current_page <1:
			current_page = 1

		self.current_page = current_page

		self.all_count = all_count
		self.per_page_num = per_page_num


		# 总页码
		all_pager, tmp = divmod(all_count, per_page_num)
		if tmp:
			all_pager += 1
		self.all_pager = all_pager

		self.pager_count = pager_count
		self.pager_count_half = int((pager_count - 1) / 2)

	@property
	def start(self):
		return (self.current_page - 1) * self.per_page_num

	@property
	def end(self):
		return self.current_page * self.per_page_num

	def page_html(self):
		# 如果总页码 < 11个：
		if self.all_pager <= self.pager_count:
			pager_start = 1
			pager_end = self.all_pager + 1
		# 总页码  > 11
		else:
			# 当前页如果<=页面上最多显示11/2个页码
			if self.current_page <= self.pager_count_half:
				pager_start = 1
				pager_end = self.pager_count + 1

			# 当前页大于5
			else:
				# 页码翻到最后
				if (self.current_page + self.pager_count_half) > self.all_pager:
					pager_end = self.all_pager + 1
					pager_start = self.all_pager - self.pager_count + 1
				else:
					pager_start = self.current_page - self.pager_count_half
					pager_end = self.current_page + self.pager_count_half + 1

		page_html_list = []
		# 添加前面的nav和ul标签
		page_html_list.append('''
                    <nav aria-label='Page navigation>'
                    <ul class='pagination'>
                ''')
		first_page = '<li><a href="?page=%s">首页</a></li>' % (1)
		page_html_list.append(first_page)

		if self.current_page <= 1:
			prev_page = '<li class="disabled"><a href="#">上一页</a></li>'
		else:
			prev_page = '<li><a href="?page=%s">上一页</a></li>' % (self.current_page - 1,)

		page_html_list.append(prev_page)

		for i in range(pager_start, pager_end):
			if i == self.current_page:
				temp = '<li class="active"><a href="?page=%s">%s</a></li>' % (i, i,)
			else:
				temp = '<li><a href="?page=%s">%s</a></li>' % (i, i,)
			page_html_list.append(temp)

		if self.current_page >= self.all_pager:
			next_page = '<li class="disabled"><a href="#">下一页</a></li>'
		else:
			next_page = '<li><a href="?page=%s">下一页</a></li>' % (self.current_page + 1,)
		page_html_list.append(next_page)

		last_page = '<li><a href="?page=%s">尾页</a></li>' % (self.all_pager,)
		page_html_list.append(last_page)
		# 尾部添加标签
		page_html_list.append('''
                                           </nav>
                                           </ul>
                                       ''')
		return ''.join(page_html_list)
